1. Field of the Invention
The present invention relates to a bicycle handlebar stem for attaching a handlebar to a steering fork on a bicycle.
2. Discussion of the Related Art
On a traditional two-wheel bicycle, the front wheel is mounted on a steering fork which is itself attached to the neck of the frame of the bicycle. The steering fork normally includes a crown, two downwardly extending front fork stays to which the front wheel is attached, and an upwardly extending steering tube which is inserted through the neck of the frame. The steering tube is essentially a pipe or tube normally made of metal, although in view of recent advancements in materials used to manufacture bicycles the steering tube might alternatively be made of advanced composite fibers or other lightweight structural material.
The handlebar is attached to the top of the steering tube with a clamping device commonly called a stem. The stem is essentially a two-ended clamp in which one end of the stem is clamped to the steering tube and the handlebar is clamped onto the other end of the stem. It is through this assembly of the handlebar, stem and steering fork that the rider is able to steer the bicycle.
In prior art stems, the clamping means for attaching the handlebar to the stem has typically been comprised of a semi-cylindrical recess in the body of the stem, a cover member with an opposing semi-cylindrical recess, and a set of at least two fasteners for fastening the top and bottom portions of the cover plate, respectively, to the body of the stem. The stem depicted in Kalloy drawing no. 85.0216 is illustrative of a common bicycle handlebar stem. In this type of device, the handlebar is essentially sandwiched between the two opposing semi-cylindrical surfaces in the cover plate and the body of the stem.
The other end of the stem has a second clamping means for attaching the stem to the top of the steerer tube on the steering fork. In prior art stems this portion of the stem has typically consisted of a common C-clamp. The Kalloy stem mentioned above is again illustrative of the type of C-clamp commonly found on many prior art stems. On the Kalloy stem, the C-clamp is comprised of a first wall portion which wraps from the body of the stem rearwardly around one side of the top of the steering tube, and a second wall portion which also wraps from the body of the stem rearwardly around the other side of the top of the steering tube. A small space separates the ends of the first and second wall portions. At least one and normally two fasteners are fastened to the ends of the first and second wall portions of the C-clamp. Tightening the fasteners consequently results in compressing the space between the ends of the two wall portions to tighten the C-clamp around the steering tube.
Although such prior art stems have proven to be functional, an improved bicycle handlebar stem is nonetheless desired.